vindex function: error when keyspace not selected

[harshit-gangal]

Description

This PR sends error message back with no database selected when a vindex function query is executed without a default database.

Example:

mysql> select * from hash where id = 4;
ERROR 1046 (3D000): no database selected: use keyspace<:shard><@type> or keyspace<[range]><@type> (<> are optional)
mysql> use customer;
Database changed
mysql> select * from hash where id = 4;
+------------+--------------------------+--------------------------+----------------------+------------------------------------+--------------+
| id         | keyspace_id              | range_start              | range_end            | hex_keyspace_id                    | shard        |
+------------+--------------------------+--------------------------+----------------------+------------------------------------+--------------+
| 0x34       | 0xD2FD8867D50D2DFE       | 0x                       | 0x                   | 0x64326664383836376435306432646665 | 0x2D         |
+------------+--------------------------+--------------------------+----------------------+------------------------------------+--------------+
1 row in set (0.00 sec)

Earlier the error was
ERROR 1105 (HY000): keyspace fetch error: node doesn't exist: /vitess/zone1/keyspaces/SrvKeyspace

Related Issue(s)

• resolves Bug Report: vindex function query not working #16519

Checklist

• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[GrahamCampbell]

Would it be possible to do global routing? Many users have one sharded keyspace and one unsharded, and usually the sharded keyspace would define the vindex functions. If the function name is unique across keyspaces, similar to tables, it would be unambiguous which one was referenced?

[harshit-gangal]

Would it be possible to do global routing? Many users have one sharded keyspace and one unsharded, and usually the sharded keyspace would define the vindex functions. If the function name is unique across keyspaces, similar to tables, it would be unambiguous which one was referenced?

This can be done, could you create a feature request for it? This is more like a nice to have, as vindex functions are not an application production query but a helpful user query.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.75%. Comparing base (eb29999) to head (bfef52d).
Report is 70 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16534      +/-   ##
==========================================
+ Coverage   68.69%   68.75%   +0.06%     
==========================================
  Files        1547     1556       +9     
  Lines      198297   199707    +1410     
==========================================
+ Hits       136228   137318    +1090     
- Misses      62069    62389     +320     

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